Location of reactive tyrosine residues in trypsin

Specificity of nitrated α‐ and δ‐chymotrypsin

“…Tyr,, -Thr,, 5 The nitration of P-trypsin did not change its esterasic or proteolytic activity. As regards the tyrosyl residues nitrated, our results confirmed those published by Holeysovsky et al [4] . On the other hand, after purification of the monomerous form of nitrated fl-trypsin we observed neither the drastic decrease of proteolytic activity (4% initial activity) found by Vincent and Ladzunski [ 181 for nitrated crystalline trypsin, nor the protective effect of benzamidine on the nitration of one tyrosyl residue.…”

“…Identification of nitrated tyrosyl residues of /3-trypsin was obtained by peptide maps from hydrolysate of nitrated sulfitolyzed /I-trypsin essentially as by Holeysovsky et al [4] .…”

“…To explore whether this modification alters also the specificity towards polypeptides, our present study was aimed at the comparison of the specificity of cleavage of the chain B of insulin by OL-and 6-chymotrypsins and their nitrated forms. The results obtained with chymotrypsiis were compared with those obtained with its structural homologue, trypsin: In contrast with previous papers dealing with the nitrated heterogeneous trypsin [3,4] , a homogeneous monomeric nitrated /3-trypsin was isolated. Its properties differ partly from those observed previously.…”

Activity and fluorescent derivatives of aminotyrosyl trypsin and trypsinogen

“…Bovine trypsin and trypsinogen contain two sets of tyrosyl residues (Inada et al, 1964;Smillie and Kay, 1961;Delaage and Lazdunski, 1965;Riordan et al, 1965;Hachimori et al, 1966;Kenner et al, 1968;Holeysovsky et al, 1969;Gorbunoff, 1969). Of the ten residues of tyrosine in trypsin (or trypsinogen), one set of five to six is "exposed," probably occupying surface positions, and the remainder are "buried" in the interior.…”